6. Phylogenetics and
taxonomy of Santalales
|The first molecular phylogeny of the sandalwood order
(Santalales) was published over 20 years ago (Nickrent and
Franchina 1990) and since those humble beginnings my
lab and collaborators have generated much information about
the evolution of this fascinating order of plants. Some
of the questions that our group has addressed include 1) how
many times has parasitism evolved? 2) how many times has the
mistletoe habit evolved? 3) are the polymorphic families
Santalaceae and Olacaceae monophyletic? and 4) what are the
relationships among the genera in the large family
Every group traditionally recognized as a family has been
examined using molecular techniques. This work was
possible only through the collaborative efforts of these
individuals: Olaceae (Dr. Valéry Malécot), Loranthaceae
(Drs. Romina Vidal-Russell and Guillermo Amico),
Misodendraceae (Dr. Vidal-Russell) and Santalaceae (Drs.
Joshua Der and Miguel A. García). The Taxon
publication (Nickrent et al. 2010) provided a complete
synopsis of current understanding of relationships in the
order, and gave a revised classification based mainly on the
During the course of this work, four new genera were named (Hondurodendron,
The reclassification of the order based on the concept
of monophyly resulted in some new (or recycled) family
names. Olacaceae was split into Aptandraceae,
Coulaceae, Erythropalaceae, Octoknemaceae, Olacaceae s.
s., Schoepfiaceae, Strombosiaceae, and Ximeniaceae.
Santalaceae was split into Amphorogynaceae,
Cervantesiaceae, Comandraceae, Nanodeaceae, Santalaceae
s. st., and Thesiaceae. Three genera
formerly classified in Santalaceae were moved to
Balanophoraceae, the order now consists of 18 families, 148
genera and nearly 2300 species. Our classification of
Olacaceae was adopted by the Angiosperm Phylogeny Group (APG
III 2009) but unfortunately they did not follow our
recommendations for "Santalaceae s. lat." and chose to lump
Viscaceae into it. My viewpoint on this was expressed in the
Haustorium newsletter found on pp. 4-6 HERE.
Answers to some of the questions raised above can now be
given. It appears that parasitism evolved just once in the
order, although more recent multigene analyses draw this
conclusion into question (stay tuned!). It seems
clear, however, that the mistletoe habit evolved five times
independently. "Santalaceae" and "Olacaceae", as
traditionally defined, were polyphyletic. In our new
classification all families are monophyletic. Thanks
to the efforts of Romina Vidal-Russell, we now have a
phylogeny for Loranthaceae. These results allowed us
to proposed the first infrafamilial classification of the
family based on phylogenetic evidence. Nuytsia
is sister to all other genera in the family and base
chromosome number shows a progressive aneuploid reduction
from X=12 in basal genera to X=9 in more derived clades
(e.g. the African members). These data literally
turned a previous biogeographic concept on its head,
highlighting dispersal, not vicariance, for the origin of
the African and Asian loranths.
126. Nickrent D. L. 2017. Status of the genera Colpoon,
Osyris and Rhoiacarpos in South Africa.
Bothalia: African Biodiversity & Conservation 47(1):
(online 13 Nov. 2017).
For a PDF
file of this article click HERE.
122. Nickrent, D. L. 2016. Ximeniaceae, Schoepfiaceae,
Comandraceae, Thesiaceae, Cervantesiaceae, Santalaceae,
Viscaceae. Pp. 404-440 in: Flora North America,
Volume 12, Flora North America Editorial Committee (eds.),
Oxford University Press, New York. For
PDF file of this article click
These treatments are available online HERE.
118. Devkota, M. P., J. Macklin, &, D.
L. Nickrent. 2015. The status of the mistletoe
Chatin (Amphorogynaceae) with a specific focus on Nepal.
Flora 215:75-83. For
a PDF file of this article click
115. Su H.-J., J.-M. Hu, F. E. Anderson and D.
L. Nickrent. 2015. Phylogenetic
relationships of Santalales with insights into the origins
of holoparasitic Balanophoraceae. Taxon 64(3): 491-506. For
a PDF file of this article click
2011. Santalales (Including Mistletoes). Encyclopedia of
Life Science. John Wiley & Sons, Ltd.:
10.1002/9780470015902.a0003714.pub2]. Wiley website
(search for article) HERE.
For a PDF file of this article
103. Ulloa, C. U, D.
L. Nickrent , C. Whitefoord, and D. L. Kelly. Hondurodendron,
a new monotypic genus of Aptandraceae from Honduras. Annals
of the Missouri Botanical Garden 97: 457-467. For a PDF
file of this article click HERE.
101. Nickrent, D. L. V. Malécot,
R. Vidal-Russell, and J. P. Der. 2010. A revised
classification of Santalales. Taxon 59: 538-558. For
PDF file of this article click HERE.
Supplemental data file on chromosome numbers HERE.
95. Vidal-Russell, R. and D.
Nickrent. 2008. Evolutionary relationships in the
showy mistletoe family (Loranthaceae). American Journal of
Botany 95: 1015-1029. For a PDF file of this article
93. Rogers, Z. S., D. L.
Nickrent, and V. Malécot. 2008. Staufferia and
Pilgerina: two new arborescent genera of Santalaceae from
Madagascar. Annals of the Missouri Botanical Garden 95:
391-404. For a PDF file of this article click HERE.
92. Vidal-Russell, R. and D.
L. Nickrent. 2008. The first mistletoes: origins of
aerial parasitism in Santalales. Molecular Phylogenetics and
Evolution 47 (2): 523-537. For a PDF file of this
article (constructed from original files, not MPE pdf that
is restricted by Elsevier), click HERE.
91. Der, J. P. and Nickrent,
D. L. 2008. A molecular phylogeny of Santalaceae
(Santalales). Systematic Botany 33: 107-116. For a PDF
file of this article, click HERE.
90. Malécot, V. and Nickrent,
D. L. 2008. Molecular phylogenetic relationships of
Olacaceae and related Santalales. Systematic Botany 33:
97-106. For a PDF file of this article, click HERE.
75. Malécot, V., D. L.
Nickrent, P. Baas, L. van den Oever, D.
Lobreau-Callen. 2004. Phylogeny of Olacaceae based on a
morphological cladistic analysis. Systematic Botany.
29:569-586. For a PDF file of this article, click HERE
60. Nickrent, D. L.,
and V. Malécot. 2001. A molecular phylogeny of Santalales.
Pages 69-74 in A. Fer, P. Thalouarn, D. M. Joel, L. J.
Musselman, C. Parker, and J. A. C. Verkleij, eds.
Proceedings of the 7th. International Parasitic Weed
Symposium. Faculté des Sciences, Université de Nantes,
Nantes, France. For a PDF file of this article, click HERE.
An updated web version of this work is HERE.
39. Nickrent, D. L. and R. J. Duff. 1996. Molecular studies
of parasitic plants using ribosomal RNA. Pp. 28-52. In: M.
T. Moreno, J. I. Cubero, D. Berner, D. Joel, L. J.
Musselman, C. Parker (eds.), Advances in Parasitic Plant
Research, Junta de Andalucia, Dirección General de
Investigación Agraria, Cordoba, Spain. For PDF file of this
article, click HERE.
20. Nickrent, D. L.
and C. R. Franchina. 1990. Phylogenetic relationships of the
Santalales and relatives. Journal of Molecular Evolution 31:
294-301. For a PDF file of the article, click HERE.